Figure 6. Chromatographic separation of retinoids from bovine ciliary processes

Retinoids were extracted from pooled ciliary processes of eyes of one-week-old calves and six- to eight-week-old cows, and analyzed on normal phase HPLC as previously described [21]. The plots show the chromatographic separation of retinoids from one-week-old (A) and from older cows (B). The peaks from older cows (B) are numbered for identification: 1 and 2 correspond to all-trans-retinyl esters (stereate and palmitate, respectively); 3 corresponds to control (etretinate); and 4 corresponds to all-trans-retinol. The negative deflection at 3 min corresponds to elution of a carotenoid, likely β-carotene (only present in older animals). The absorption spectra of components 1, 2, 4, and the carotenoid, are shown in insets (B). The elution profile of retinoids was obtained at 325 nm.